Display Permissions

• By default, only you can use the display
  and only locally

• You can use xhost to allow/disallow connections
  xhost +orca : allow anyone on orca to use your display
  xhost + : allow anyone anywhere to use it
  xhost - : disallow other machines/users

• X creates ~/.Xauthority which has a magic cookie

• xauth can manipulate .Xauthority
  xauth nextract - roach:0 | ssh orca xauth nmerge -

• X clients use DISPLAY variable to locate the server
  export DISPLAY=tec207ws21:0
  handled by telnet and ssh

• ssh sets up a virtual server